U.S. patent number 5,775,636 [Application Number 08/723,069] was granted by the patent office on 1998-07-07 for guided artillery projectile and method.
This patent grant is currently assigned to The United States of America as represented by the Secretary of the Army. Invention is credited to John R. Vig, Steven W. Waugh.
United States Patent |
5,775,636 |
Vig , et al. |
July 7, 1998 |
Guided artillery projectile and method
Abstract
A guided artillery projectile is provided for use in improving
its accuracy while spinning. The projectile includes an artillery
shell, a plurality of movable fins, fin actuators for
two-dimensional steering, a fin control for the fin actuators, and
a guidance unit for the fin control. A method of guiding an
artillery projectile is also provided.
Inventors: |
Vig; John R. (Colts Neck,
NJ), Waugh; Steven W. (Alexandria, VA) |
Assignee: |
The United States of America as
represented by the Secretary of the Army (Washington,
DC)
|
Family
ID: |
24904705 |
Appl.
No.: |
08/723,069 |
Filed: |
September 30, 1996 |
Current U.S.
Class: |
244/3.24;
244/3.21; 244/3.23; 244/3.26 |
Current CPC
Class: |
F42B
10/64 (20130101) |
Current International
Class: |
F42B
10/64 (20060101); F42B 10/00 (20060101); F42B
010/00 (); F41G 007/00 () |
Field of
Search: |
;244/3.11,3.21,3.23,3.24,3.26 ;102/213 |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
Hollis, Michael S.L., "Preliminary Design of a Range Correction
Module for n Artillery Schell", Army Research Laboratory Report
ARL-MR-298, Mar. 1996..
|
Primary Examiner: Jordan; Charles T.
Assistant Examiner: Wesson; Theresa M.
Attorney, Agent or Firm: Zelenka; Michael
Government Interests
GOVERNMENT INTEREST
The invention described herein may be manufactured, used, imported,
sold, and licensed by or for the Government for governmental
purposes without the payment to us of any royalty thereon.
Claims
What is claimed is:
1. A projectile comprising:
a shell having an axis;
a plurality of air deflectors mounted on the shell and movable
relative thereto;
actuating means connected to the air deflectors for providing
steering of the projectile during spinning thereof without the need
to despin any portion of the projectile;
control means for controlling the actuating means;
a guidance system including a GPS receiver for providing
information to the control means; and
a fuse unit for detonation of the projectile upon actuation of the
fuse unit and wherein
the actuating means includes a plurality of cylinders with pistons
respectively connected to the air deflectors for movement of the
air deflectors in a radial direction at a rate in synchronism with
a spin rate of the projectile; and wherein
said air deflectors are fins.
2. The projectile of claim 1, wherein
the actuating means includes a plurality of piezoelectric layers
respectively connected to the fins for bending of the fins for
steering of the projectile.
3. The projectile of claim 1 wherein
the fuse unit has a detonator which is actuated at a selective
trajectory point by the guidance system.
4. The projectile of claim 1 wherein
the guidance system has means to prevent detonation unless the
projectile lands within a specified pre-programmed area.
5. A method of guiding a spinning projectile toward a selected
target including the steps of:
utilizing a GPS receiver carried in the projectile to determine the
position of the projectile relative to the target;
providing a selective shell having bendable, relatively movable
fins which project radially outwardly in an in-out movement during
the spin of the projectile, said in-out movement occurring at some
rate;
controlling the rate of in-out movement of the fins in synchronism
with the rate of the spin of the projectile;
controlling the bending of the movable fins for steering the
projectile or target;
determining the velocity change, direction change, spin rate and
orientation for the control of the steering of the projectile to
the target.
6. The method of claim 5, wherein the selective shell is an
artillery shell.
7. The method of claim 5, wherein determining the velocity change
and direction change and spin rate and orientation includes sensing
of the emissivity between the earth and sky for determining spin
rate and orientation.
Description
FIELD OF THE INVENTION
The invention described herein generally relates to a guided
artillery projectile device and method, and in particular the
invention relates to a guided artillery projectile device having an
artillery shell having a front assembly with relatively movable
fins or air-deflectors and a guidance unit disposed inside the
artillery shell front assembly for operating the fins/air
deflectors while the projectile is in flight and spinning.
BACKGROUND OF THE INVENTION
The prior art artillery projectile is virtually the same as the one
used fifty years ago. The prior art artillery projectile is
inaccurate, especially at long range. Once the prior art artillery
projectile is fired, it is ballistic. Its accuracy is relatively
poor because factors such as weather and minor variations in
initial conditions of firing can result in large inaccuracies.
One problem with the prior art artillery projectile is that its
accuracy is relatively poor.
A second problem is that the projectile typically spins at about
300 revolutions per second upon firing and at about 200 revolutions
per second down range, and this makes it difficult to guide the
projectile.
With the advances in microelectronics, microelectromechanics,
sensor and navigation technologies, it has become possible not only
to accurately and continually determine the position of an
artillery projectile, but also to control the projectile's
trajectory. The Global Positioning System (GPS) has made it
possible to rapidly and accurately determine the position of an
object anywhere on earth, in any weather, 24 hours a day. As the
size and cost of GPS receivers and inertial measurement units (IMU)
have declined, it has become more and more feasible to employ GPS
and IMUs for guiding projectiles.
Trajectory control methods and devices, with emphasis on a "D-ring
correction module," are described in Army Research Laboratory
Report ARL-MR-298 by Michael S. L. Hollis, "Preliminary Design of a
Range Correction Module for an Artillery Shell," March 1996. The
D-ring correction module can provide one-dimensional, i.e., range,
correction only. A method that has been proposed for obtaining
two-dimensional correction uses a motor to despin the front part of
the projectile. This front part contains canards (fins), among
other parts, which are used to correct the trajectory of the
projectile.
As there are many millions of artillery projectiles in inventory,
in the development of guided projectiles, the main emphasis has
been on methods that would allow the modification of existing
projectiles, rather than on the design of a new type of projectile.
That is, the goal has been to replace the fuse of existing
projectiles with a device of similar size and shape, the
replacement device containing, in addition to the fuse, a GPS
receiver and IMU, a trajectory correction mechanism, and a power
source.
The present invention provides a new type of trajectory control
mechanism which requires no despinning, which utilizes a GPS
receiver to guide the projectile toward its target and which is
applicable to both existing projectiles and to projectiles of new
designs.
SUMMARY OF THE INVENTION
According to the present invention, an artillery projectile is
provided. This artillery projectile includes an artillery shell, a
plurality of fins mounted on the shell and movable relative
thereto, each fin having actuating means for providing two
dimensional steering of the projectile during projectile spinning,
a control means for controlling the actuating means, and a guidance
unit for providing information to the control means.
By using the guidance unit, initial errors introduced into the
ballistic trajectory are calculated and corrected for during flight
by manipulation of the fins or air deflectors, thus significantly
improving overall projectile accuracy.
By using the unique actuators and fins/air deflectors synchronized
with the spin of the projectile, spinning of the projectile does
not interfere with the guidance.
BRIEF DESCRIPTION OF THE DRAWINGS
The foregoing and other objects, features and advantages will be
apparent from the following description of the preferred embodiment
of the invention as illustrated in the accompanying drawings.
FIG. 1 is an elevation view of a complete artillery projectile
including an embodied fuse unit, according to the invention;
FIG. 2 is a sectional view as taken along the line 2--2 of FIG.
1;
FIG. 3 is a sectional view as taken along the line 3--3 of FIG.
1;
FIG. 4 is an enlarged view of a portion of FIG. 1;
FIG. 5 is a sectional view as taken along the line 5--5 of FIG.
4;
FIG. 6 is a sectional view as taken along the line 6--6 of FIG.
5;
FIG. 7 is a sectional view as taken along the line 7--7 of FIG.
6;
FIG. 8 is a block diagram of a circuit of a guidance unit in FIG.
3.
DESCRIPTION OF THE PREFERRED EMBODIMENT
As shown in FIGS. 1 and 2, a complete artillery projectile 2 is
provided. Projectile 2 has a front assembly 4 and a rear assembly 6
which have an axis 8. Front assembly or fuse assembly 4 has an
embedded guidance unit or package 10, a fuse unit 12, and a control
circuit unit 14. Front assembly 4 also has a threaded projection
16, which is received in a threaded recess 17 in end wall 15 of
rear assembly 6. Rear assembly 6 is a standard ordinance shell
assembly. Front assembly or fuse device 4 replaces a fuse portion
of the standard ordinance shell assembly. Front assembly 4 has a
longitudinal, outer profile which fairs into and matches the
longitudinal outer profile of rear assembly 6. Fuse unit 12 has a
detonator (not shown) which is actuated by an impact force.
Alternately, trajectory position or altitude can be used to actuate
the detonator, using a signal from guidance unit 10 to fuse unit
12. Also, the guidance unit 10 has means (not shown), which prevent
detonation unless projectile 2 lands within a specified
pre-programmed area. Guidance unit 10 has a power source (not
shown) for supplying power to units 10, 12, and 14. Guidance unit
10 also contains a GPS receiver and antenna (not shown), and may
also contain an inertial measurement unit (IMU) and a central
processing unit (CPU). The outer surfaces of front assembly 4 and
rear assembly 6 are shown in FIGS. 1 and 2 as cylindrical, for ease
of illustration. Alternately, the outer surfaces can taper towards
the front end.
Front assembly 4 has a peripheral wall or casing 18, which supports
fuse unit 12, a front tapered wall portion 20, which supports
guidance unit 10, a partition wall 22, which supports unit 14, and
a rear wall 24.
Front assembly 4 has a top fin 26, a bottom fin 28, a left fin 30
and a right fin 32, which are air deflectors, and which are
radially movable for extension and retraction thereof, and which
are bendable for steering projectile 2. Front assembly 4 has a
front cavity 34 for units 10, 12, 14, and has a rear space 38 for
the fins 26, 28, 30, 32. Cavity 34 may also contain explosive
material (not shown).
As shown in FIGS. 4, 5, 6, 7, top fin 26, which is identical in
construction to bottom fin 28, left fin 30 and right fin 32, has a
top actuator 40 and has a top blade or core 42. Top actuator 40 has
a cylinder 44 and a piston 46. Piston 46 is welded or fixedly
connected to blade 42. Cylinder 44 is supported on a common support
hub 48, which has support spokes or struts (not shown). Actuator 40
is an electromechanical type of actuator. Piston 46 and fin 26 move
in a radial direction 50 towards and away from shell 12. Blade 42
is guided by a channel 51. Cylinder 44 is a high speed vibrator, or
the like.
Blade 42 has first and second faces 52, 54. Faces 52, 54 have
respective pairs of piezoelectric layers 56, 58, which are bonded
thereto. Layers 56, 58 are electrically interconnected in order to
bend blade 42. Layers 56, 58, expand and contract in opposite
lengthwise directions 60 in order to bend blade 42. Blade 42 is
displaced in a transverse direction 62 in order to steer projectile
2. Blade 42 during operation has a variable blade projection 64,
and has variable transverse displacements or bend distances 66,
67.
As shown in FIGS. 1 and 8, guidance system 10 includes a visible
light photodetector 68, and infrared (IR) detector 70, an
orientation unit 72, a positioning subsystem (GPS) 74, and a fin
control unit 76. Units 68, 70, 72, 74, 76 each has a power supply
connection (not shown) and has a ground connection (not shown).
Photodetector 68 has an output conductor 78, which is connected to
an input 80 of orientation unit 72. IR detector 70 has an output
conductor 82, which is connected to an input 84 of orientation unit
72. Detectors 68 and 70 provide day and night sensing of the
horizon.
GPS unit 74 has a first output conductor 86, which is connected to
a first input 88 of fin control unit 76. GPS unit 74 also has a
second output conductor 90, which is connected to a second input 92
of fin control unit 76.
Orientation unit 72 has an output conductor 94 which is connected
to a third input 96 of fin control unit 76; and has a second output
95, connected to input 97.
Fin control unit 76 has respective first and second and third and
fourth output conductors 98, 100, 102, 104, which are respectively
connected to fin actuators 106, 108, 110, 112. Fin control unit 76
has respective fifth and sixth and seventh and eighth output
conductors 114, 116, 118, 120, which are respectively connected to
pairs of piezoelectric layers 122, 124, 126, 128.
Conductor 86 provides velocity change signals. Conductor 90
provides direction change signals. Conductor 94 provides
orientation signals. Conductor 95 provides spin rate signals.
Using projectile 2, it is not necessary to despin the projectile 2,
before using its guidance system 10. The same or better results are
obtained by means of the movable fins 26, 28, 30, 32, which
protrude from the projectile 10. The motions of fins 26, 28, 30, 32
are synchronized with the spin rate of the projectile 2, such that
the fins 26, 28, 30, 32 protrude or project an appropriate distance
64, and for an appropriate duration, always at the orientation
required for guiding projectile 2 to its target. The orientation of
projectile 2 is determined by the combination of the visible light
photodetector 68 and the IR detector 70, for respective use in day
and night operations. When the IR detector 70 is an uncooled
thermal detector, such as a silicon micromachined bolometer, it may
be suitable for use at both day and night times, thus eliminating
the need for a separate photodetector. The difference in emissivity
between the earth and the sky is sufficient for the determination
of the projectile's orientation. The GPS unit 74 is used to decide
the direction and velocity changes needed. The detector 68 or 70
determines the projectile's orientation and the outputs from the
detectors 68, 70 are used as inputs to the control unit 76, which
controls the fins 26, 28, 30, 32. The fins or air deflectors 26,
28, 30, 32 move in and out in synchronism with the spin of
projectile 2, and avoid the need to despin the projectile 2.
The method of guiding the artillery projectile 2 includes the steps
as indicated hereafter:
provide an artillery projectile 2 having relatively movable fins
26, 28, 30, 32 which are recessed in the projectile 2 during its
firing and which project radially outwardly in an in-out movement
during spin of the projectile;
control the rate of in-out movement of the fins 26, 28, 30, 32 in
synchronism with the rate of the spin of the projectile 2;
control the movable fins 26, 28, 30, 32 for steering of the
projectile 2 to a target; and
determine the velocity change and direction change for the control
of the steering of the projectile 2 to the target.
The advantages of projectile 2 are indicated hereafter.
A) Projectile 2 avoids the problem of poor accuracy.
B) Projectile 2 avoids the need to despin the projectile before
using its guidance system.
C) One can use an existing inventory projectile, simply augmented
with a new fuse unit.
To minimize the energy required for the in and out movement of the
fins, some of the energy required for the outward motion can be
recovered during the inward motion.
While the invention has been described in its preferred embodiment,
it is to be understood that the words which have been used are
words of description rather than limitation and that changes may be
made within the purview of the appended claims without departing
from the true scope and spirit of the invention in its broader
aspects.
For example, instead of fins 26, 28, 30, 32, all piezoelectrical
fins or flaps can be used.
As a second example, instead of the GPS positioning subsystem, an
inertial measuring subsystem or a doppler subsystem can be used,
for providing information about the necessary velocity and
direction changes.
As a third example, the invention may be applied not only to
artillery projectiles but also to other types of precision guided
munitions.
As a fourth example, a hinged flap can be used in place of blade
42.
As a fifth example, the detonator (not shown) of fuse unit 12 can
be actuated at a selective altitude instead of by an impact
force.
* * * * *